Method of making knife blades



Feb. 5, 1952 a MlLLER 2,584,470

METHOD 0F MAKING KNIFE BLADES Filed oct. 15, 195o {'Q j 15 /ZF FW 5% @my Z131 4 l IIIIIII lll! s www Patented Feb. 5, 1952 UNITED STATES PATENT OFFICE METHOD 0F MAKING KNIFE BLADES Bernard Miller, Sheield, England Application October 13, 1950, Serial No. 189,965 In Great Britain August 17, 1950 6 Claims. 1

This invention relates to the manufacture of table and like knives with solid forged bolsters.

In the manufacture of such table and like knives it is usual for the blade, bolster and tang to be forged by drawing down the blade and tang from stock of a section large enough to afford the bolster between them. This provides a black forging with an irregular outline to the blade, from which the proper shape is produced by cutting away excess metal in a die. Afterwards the blade is hardened and then with the bolster, ground and polished. These operations require much work and result in a substantial loss of According to the present invention, bright 5"' hardened stock is taken of a section substantially that of the iinished blade, and is iirst punched out to the outline of the blade with an allowance for tang and bolster, the bolster is then upset by electrical upsetting process and is formed be- -1 tween dies, and the blade is then completed by glazing and polishing the bolster.

Ey electrically upsetting the bolster the temper and sin-tace of the blade is not interfered with; therefore no subsequent hardening operation is necessary and the finishing operations are substantally reduced to that on the bolster, little or no work on the blade itself being required, except sharpening the edge.

Preferably the vice jaws which grip the tang L portion of the work in the electrical upsetting operation are shaped to upset a short root portion of the tang into a thickened or rounded shape and if desired in a subsequent operation the remainder of the tang can. be heated and thickened by edgewise pressure on the part of the stock which is left.

If this is done the nished blade has all the features of a blade forged in the black in the way hitherto usual, without any of the prolonged grinding necessary to bring a hammered or rolled blade to a 'line flat finish and without the loss of metal consequent upon such grinding.

Bright finished hardened tapered-section stock such as is required for the initial material according to this invention can be produced with great uniformity of quality and correct temper of the finished blade so that variations of temper in the knives are automatically obviated, no straightening operations, such as are commonly required after hardening, are called for and the product is a superior article of cutlery.

One example of a specific form of the process according to the present invention will now be described with reference to the accompanying drawing, in which:

Figure l shows the form of blanks punched from the strip of hardened and polished stock according to the present invention,

Figure 2 is a cross-section of the stock,

Figure 3 shows the blank viewed edgewise after upsetting a bolster section therein,

Figure 4 is a similar View with the bolster dieshaped to its final form,

Figure 5 shows the parts in a state shown in Figure 4, but with the blade viewed flatwise,

Figure 6 shows the tang after it has been compressed edgewise to thicken it,

Figure 7 is an end-view of a tang as shown in Figure 6,

Figure 8 is a diagrammatic plan of the upsetting apparatus.

Referring to Figure l, a strip II is taken of hardened, tempered and polished stainless steel. This strip is commercially producible in long lengths and is of tapered section as seen in Figure 2, the back being thicker than the opposite edge. The dimensions of the strip are such as to afford a blank, when punched therefrom, which is of the right thickness for the completed knifeblade, and which needsnonly sharpening along the thin edge, without any material removal of the metal from the polished surfaces. As shown a blank I 2 is punched from said strip in the form of a knife-blade with a tank portion I3 extending from it. The tang portion is wider than that eventually required for the tang, and somewhat longer. The blank is punched so that as much as possible of the edge of the blade extends along the thin edge of the strip and so that the back of the blade where it is nearest to the tang touches the thicker edge of the strip. The tang itself is punched as far as possible from the thicker portion of the strip. Although the strip is hardened and tempered, it is possible to punch blanks therefrom as the temper is not so hard as that which can be imparted to punches and dies, and the operation of punching a knife blank from such strip is known in itself.

The first operation upon the blank I2 after punching is to upset a bulge in the blank as shown at I4, Figure 3, at the junction between the blade and the tane. |This is done in the manner hereinafter explained in connection with E of the drawing. The upset portion I is such r, as to contain the correct amount oi metal for the bolster eventually required, and also cc; prises an embryo end portion |5 of the tang. The bulk of the tang, however, is left of the thiol;- ness of the original stock from which it was punched. The bolster I4 is formed by pressure between dies to the shape shown at il?, Figure 3 or to any other desired shape which may ca for by the fashion chosen for the knife. T is eiected either het, while the piece is still hot from the upsetting operation, or in a subsequent operation as may be found desirable.

The above operations leave the tang I3 still flat, but joined to the bolster le tially-upset circular portion I5. Any die oper bolster .f3 is tr nined away, and the bien is lett broader than the circular portion l, is neat edgewise between so as to reduce it to the dirne siens o tion I5, in the plane oi the blade l2, thicken it laterally as shown in The dies enployed for this purpou ened or serrated surfaces gripping quail' inserted in the knife handle. wise pressure on the flat taneI is is inushrccnied over along each edge, invii certain amount of hollow space as Figures and 7. Such hollow further i grip of the tang in the handle. but the holle i not persist right up to the bolster :t of the metal having been electrica-v a round form close desirable to heat the tang before pressing it wise, at least surliciei to draw the temp-Pr the metal, and if necessary to a forging .as shown in Fig .re 5, the back o the blade is bevelled as indicated at i3, and when the slight degree of oxidation which occurs close to the bolster' has been removed by glazing and polishing and the edge has been sharpened, the blade is ready i r insertion in the handle in known manner.

Referring to Figure 8, the electrical upsetting apparatus coinp a bed 2i; having longitudine.. guideways El, 22 in which operate two sli-ders 213 and The slider 23 carries two transversely movable 'vice jaws 35, 26, which are o1 ward one another by a right-hand n screw 3l, and hand-wheel These vice jaws are made oi" bronze, and are electrically connect-e" by rlexible lead 29 to one terminal of the low 'rcitag'e secondary winding 5G of a step-d trical ":ansformer having a primary windii g The vice jaws 25, 2e are shaped to ,tit the lade portion I2 oi the knife-blank. The slide '25 carries vice jaws 3|, 32, which are adapted to oe forced towards one another to grip tang bv rightand left-hand screw 33 operated by an end-wheel 34. The vice jaws 3 I, 32 are connected ilo ible lead 35 to the other terminal o1 the secondary winding 5Fl orthe transformer hereinbeore referred to. The jaws 3i, 3?. are insulated from the aws E 25 in manner known se and are recessed as shown at 33 to afford spac each side ci the knife lanl for the metal of the blanl: to flow, when softened, and to .form

portion '-.vhicl may be produced in t portion l5 of the tang as indicated in gures 3 to 7. The slider 24 is connected by connectingrods 31, 38 to a cross-head 39, and the cross-head is engaged by a ram 40. The ram 40 is operated by hydraulic cylinder not shown in the drawing so as to move the cross-head 3S to the left as shown in the ligure, when suitable pressure is applied in the cylinder, and thus to carry with it the slide 24 and the vice jaws 3|, 32. The slide 23 is operated upon by a ram 4|, which may be either yieldingly pressed by spring means, or hydraulically operated, or otherwise, as desired, to move the vice jaws 25, 25, to the lei't as shown in the figure.

Behind the slider 24, considered in the direction of the length of the machine there is a wedge-shaped structure consisting of two upstanding blacks 42, 43, between which are two wedge vice jaws 44, 45, adapted to grip the end of a push rod 45 rmly and to sustain it against pressure exerted on the tang I3.

In operation a knife-blank I2 is gripped rmly between the movable vice jaws 25, 2li and also gripped at the tang end between the intermediate vice jaws 3|, 32. The intern ediate vice jaws 3l, 32 are so adjusted as not to grip the tang so rmly as to prevent them sliding along it. Current being now applied, the portion of the blank. between the jaws 25, 25 on the one end, and the jaws 3|, 32 at the other, becomes hea d bv the passage of the electric current to forging ternp rature, and the pressure applied by the ram #il compresses the nieta-l, forming an upset portion between the two pairs of jaws. As the upsetting operation proceeds, the intermediate vice jaws 3|, 3'? are caused to slide along the knife blank to the left sufhciently to expose fresh metal to the electric current and to the upsetting operation until an upset is produced similar to that shown Figure 3. By suitable regulation the current, the upsetting operation is carrie: out at a temperature which is maintained within forging temperature of the steel, and, surprisingly, it is found that although the steel is 'forged in the bolster portion, the remainder of the blade where it is gripped 'oy the vice jaws 3 I, 32 does not have its temper drawn, but remains bright and polished and of goed temper suitable for a knife blank..

It will be seen, therefore, that the present invention, starting from hardened, tempered and polished stock, a bolster is forged in one piece with the knife-blade without altering the temper of the blade, and without demanding those extensive grinding and polishing operations upon forged metal which are commonly essential in the production of a solid forged blade.

The resultant saving in the met-al employ d as compared with the usual process for blackforging the whole blade, followed by grind polishing, hardening and tempering. i" very corsiderable, and the blades accor invention are not only of the h .0. are more easily mass-produc u i .ith 1.', ormity, both of temper, sharpn. es. .1, Y. than has been possible in the manuiactu ci cutlery hitherto.

I claim:

l. A process for the production ol solid `forged knife blades, wherein bright hardened stoel; a section substantially that oi the fir ed used, comprising punching out i oi.. blade and integral tang from the stock, u; a bolster by heating the portion betr-.vav lade and tang and applying pres. blade axially thereof to bulge out' heated portion and pressing the bulged porti-cn between dies to shape the bulged portion into s. complete bolster.

2. A process for the production of solid forged knife blades, wherein bright hardened stock of a section substantially that of the iinished blades is used, comprising punching out the outline of a blade and integral tang from the stock, upsetting a bolster by electrically heating the portion between the blade and tang and applying pressure to the blade axially thereof to bulge outwardly the heated portion and pressing the bulged portion between dies to shape the bulged portion into a complete bolster.

3. A process as claimed in claim 2, including the step, simultaneous with the upsetting of the bolster, of upsetting a short root portion of the tang.

4. A process as claimed in claim 2, including the subsequent step of compressing the tang transversely of its axis to thicken it.

5. A process for the production of solid forged knife blades, wherein bright hardened stock of a section substantially that of the finished blades is used, comprising punching out the outline of a blade and integral tang from the stock, upsetting a bloster by electrically heating the portion between the blade and tang and applying pressure to the blade axially thereof to bulge outwardly the heated portion, placing the bulged CTL portion between dies to shape the bolster, and subsequently polishing the bolster.

6. A process for the production of solid forged knife blades, wherein bright hardened stock of a section substantially that of the nished blades is used, comprising punching out the outline of a blade and integral tang from the stock, upsetting a bolster by electrically heating the portion between the blade and tang and applying pressure to the blade axially thereof to bulge outwardly the heated portion and pressing the bulged portion between the dies to shape the bulged portion into a. complete bolster, cutting olf the flash around the bolster and polishing the bolster.

BERNARD MILLER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 515,835 Lombard Mar. 6, 1894 1,967,479 Platts July 24, 1934 2,081,011 Lautmann May 18, 1937 2,184,150 Parker et al Dec. 19, 1939 2,552,103 Miller May 8, 1951 

